Ah, that would explain it. I appreciate you making me aware. It will be a whole lot harder to check when everything is back together.
So, did I read you right? you just eliminated the check valve on the air vent? Did you keep the lines small, like a # 6 to keep water bleed off to a minimum?:bigear:
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Thread: 38 Top Gun Cooling Problem
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08-09-2009 07:36 PM32' Fever (Off to Syracuse) and 36"Gladiator; FORD powered
Cause somebody has to!
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08-09-2009 07:46 PM
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08-09-2009 08:54 PMI agree, with below the water line is a better installation than what we had on the Top Gun, sorry the thru-transom fittings were already there.
What makes the difference on the clear hose after the engine or between the sea-strainer and the pump if looking for air coming into the system?www.merperformancemarine.com
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08-09-2009 08:59 PMI have two reasons that immediately come to mind. First the pressure before the motor will be greater that the clear hose is designed to handle. Second the water is under pressure collapsing the bubbles. By the time the water has entered the engine the pressure has fallen, the bubbles have expanded and it is easier to see them.
Mercury has recommended 25 lbs at wide open on most engines. In the race boats you only want to scoop what is necessary. I understand 15lbs is the bare minimum an engine will tolerate. If steam pockets are forming adding air to the water it is here where you will find evidence of it.Last edited by MOBILEMERCMAN; 08-09-2009 at 09:06 PM.
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08-09-2009 09:44 PMFirst of all, I was asking a honest question, with no smartness intended. The clear hose I used is pretty thick, has been on with alot of time in use, yesterday to be a matter fact in the ocean. It's coming off anyways. Also with the issues addressed in this thread, I have read the water pressures at the cross-over, at the block drain and at the intake manifold they haven't been different than 5 psi. What I noticed, before this thermostat housing issue was found that the water pressure would bounce about 5-8 psi at the intake at cylinder # 1 location and that was the steaming affect of the water. I agree with you that 15 psi minimum for this, I also like 25 psi min. pressure we had 25-30 psi, what caused our problem is the cold water from the by-pass confusing the thermostat, allowing the water on cylinders 1-7 to develope steam pockets, and you are right in saying that using the clear hose between the engine and the exhaust would show the bubbles. Our problems came from a part that wasn't engineered the same way that Stainless Marine designed their's. What have you seen for pressure drops from the sea strainer to the water inlets on the block. Thanks Mark
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08-09-2009 09:58 PMMark, I am not an engine guy, I am only sharing what I have learned while rigging and racing boats. I have been fortunate to work with some great people and have witnessed much in the progression of water systems in Fountain race boats.
The last thing I have to add with the clear hose is you can extend it into the cockpit and monitor it easily while underway.
Thank you for the thread, following it though, and sharing your results.
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08-09-2009 10:02 PMMobilemerman, went back and read your post on the clear hose, at that time I was looking at the water pick-ups, merc water dumps and sea-strainers. I saw you said; between the engine and the headers. Sorry you had to repeat that to me, I over looked that.
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08-09-2009 10:08 PMThanks Jim, you have great knowledge. I usually don't have to get into rigging issue of this kind, as you can see, something not tested for every application.
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08-09-2009 10:12 PMI have only attempted to measure in the stainer unsuccessfully. AT test between 130 and 140 mph the 250 lb gauge would explode in one short test run. I would read the pressure in the block drain. I never experimented with the areas in between. The focus was on carrying just enough pressure to keep steam from forming and passing only water void of air through the engine. The engine guys we worked with dealt with the issues of flow through the engine as you have here. That part I have no experience to assist you with.
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08-09-2009 10:22 PMI guess I can close this subject one this. Heres the deal: Water cross-overs and thermostats housings are not created equal. Eddie Marine needs to change the design for HP, not drill holes in the thermostat until nothing is left of it. Stainless Marine has it engineered correct, keep the by-pass water away from the thermostat confusing it. What did it take to fix: plug the by-pass on the cross-over and drill & tap the front side of the intake to 1/2 npt and by-pass warm water to the thermostat housing with #10 an. Temps stay between 140 -150 degrees at all rpms and after bringing off plane back to idle in gear.
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08-09-2009 10:26 PMwww.merperformancemarine.com
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08-09-2009 10:36 PMNot many boats have speedos anymore. Now its all GPS. According to Livorsi a speedo is a pressure gauge where 70 mph is the break even point 70mph =70 or 71 lbs,,,, 100mph=144lbs. Add a little compressed air from under the boat and a few pressure spikes and gauge went pop.